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Actors have become widespread in programming languages and programming frameworks focused on parallel and distributed computing. While actors provide a more disciplined model for concurrency than threads, their interactions, if not constrained, admit nondeterminism. As a consequence, actor programs may exhibit unintended behaviors and are less amenable to rigorous testing. We show that nondeterminism can be handled in a number of ways, surveying dataflow dialects, process networks, synchronous-reactive models, and discrete-event models. These existing approaches, however, tend to require centralized control, pose challenges to modular system design, or introduce a single point of failure. We describe “reactors,” a new coordination model that combines ideas from several of the aforementioned approaches to enable determinism while preserving much of the style of actors. Reactors promote modularity and allow for distributed execution. By using a logical model of time that can be associated with physical time, reactors also admit control over timing.
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Reactors: A Deterministic Model for Composable Reactive Systems
NOTE: DOI IS available but the nsfpar system rejects it: 10.1007/978-3-030-41131-2_4 This paper describes a component-based concurrent model of computation for reactive systems. The components in this model, featuring ports and hierarchy, are called reactors. The model leverages a semantic notion of time, an event scheduler, and a synchronous-reactive style of communication to achieve determinism. Reactors enable a programming model that ensures determinism, unless explicitly abandoned by the programmer. We show how the coordination of reactors can safely and transparently exploit parallelism, both in shared-memory and distributed systems.
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- Award ID(s):
- 1836601
- PAR ID:
- 10188807
- Date Published:
- Journal Name:
- Model-Based Design of Cyber Physical Systems (CyPhy'19)
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Many programming languages and programming frameworks focus on parallel and distributed computing. Several frameworks are based on actors, which provide a more disciplined model for concurrency than threads. The interactions between actors, however, if not constrained, admit nondeterminism. As a consequence, actor programs may exhibit unintended behaviors and are less amenable to rigorous testing. We show that nondeterminism can be handled in a number of ways, surveying dataflow dialects, process networks, synchronous-reactive models, and discrete-event models. These existing approaches, however, tend to require centralized control, pose challenges to modular system design, or introduce a single point of failure. We describe “reactors,” a new coordination model that combines ideas from several of these approaches to enable determinism while preserving much of the style of actors. Reactors promote modularity and allow for distributed execution. By using a logical model of time that can be associated with physical time, reactors also provide control over timing. Reactors also expose parallelism that can be exploited on multicore machines and in distributed configurations without compromising determinacy.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Conference Paper:
- https://doi.org/10.1007/978-3-030-41131-2_4
